Polyurethanes containing reactive silane groups, also referred to as silane-terminated polyurethanes (STPs), and their use as sealants and adhesives are known and described, for example, U.S. Pat. No. 5,554,709 describes a moisture-curing alkoxysilane-terminated polyurethanes which can be obtained by reacting polyurethane prepolymers with sulfur-free alkoxysilanes. U.S. Pat. No. 4,857,623 describes alkoxysilane-terminated, moisture-hardening polyurethanes obtained by reaction of hydroxy-terminated diols and/or triols with diisocyanates to form isocyanate-terminated polyurethanes, and U.S. Pat. No. 6,197,912 describes moisture curable polymers having terminal or pendant silyl groups that exhibit improved thermal stability, elongation, and tear resistance.
U.S. Pat. No. 4,985,491 discloses a polyether triol fabricated in the presence of a double metal cyanide catalyst that is reacted with a polyisocyanate to produce an isocyanate-terminated prepolymer. The prepolymer is then chain-extended to produce the desired sealant. U.S. Pat. No. 4,481,367 discloses prepolymers, which result from reacting a short chain glycol with substantial excess of diisocyanate to form linear urethane prepolymer terminated with isocyanate groups.
A curable resin composition containing an oxyalkylene polymer having a functional group such as a hydroxyl, epoxy or isocyanate which is directly reacted with a compound having a silicon-containing reactive group is disclosed in U.S. Pat. No. 5,910,555.
However, a disadvantage of these moisture-curable polymers is the presence of urethane groups, which causes the products to have a high viscosity. To achieve suitable application viscosities, the high viscosity is reduced by the addition of higher amounts of plasticizer and lesser amounts of fillers, resulting in more expensive sealant products.
Accordingly, it is an object of the present invention to provide moisture-curable silylated polymer that can be prepared with lower viscosities and improved physical properties at reduced costs. The products of the present invention are suitable for use as sealants, adhesives and coatings.
All of the United States Patents disclosed herein are incorporated by reference.